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Bacillus subtilis is a common probiotic that is widely used in agriculture and the environment. In recent years, researchers have found that Bacillus subtilis has a significant effect on plant growth and stress resistance.
Among them, it has a dramatic effect on the growth physiology of forsythia under cadmium stress. As a common Chinese medicinal herb and garden plant, Forsythia has important economic and ecological value.
However, modern industrialization and human activities have led to the accumulation of cadmium in the environment, which seriously threatens the growth and quality of Forsythia. Cadmium is well known to be toxic to plants, it can inhibit the growth and development of plants and destroy their physiological functions.
In this context, researchers began to explore the use of Bacillus subtilis to mitigate the negative effects of cadmium stress on forsythia.
Early studies have shown that Bacillus subtilis can significantly increase the growth rate and biomass of Forsythia under cadmium stress, and enhance its antioxidant capacity. This has sparked interest in how Bacillus subtilis exerts this promoting effect.
This paper aims to deeply explore the physiological effects of Bacillus subtilis on the growth and physiology of Forsythia under cadmium stress, in order to provide scientific basis for environmental remediation and improvement of plant stress tolerance.
Starting from the effects of cadmium stress on forsythia, we will introduce the tolerance of Bacillus subtilis under cadmium stress and explore in detail the mechanism of its influence on the growth physiology of forsythia.
By in-depth understanding of the latest research progress in this field, we will reveal the potential of Bacillus subtilis in cadmium stress mitigation, and provide new ideas and methods for ecological environmental protection and sustainable agricultural development.
Effects of cadmium stress on forsythia growth
Cadmium is a common heavy metal element that is widely found in soil, water and air. The sources of cadmium mainly include smelting, coal combustion, waste discharge and agricultural fertilization.
However, because cadmium is highly toxic and bioaccumulative, it poses a serious threat to plant growth and environmental health.
Forsythia, also known as honeysuckle, is a common herb that is widely used in traditional Chinese medicine and horticulture. However, forsythia has a high sensitivity to cadmium and is susceptible to cadmium stress.
In the case of cadmium stress, the growth and development process of forsythia is severely limited. Cadmium stress has a multifaceted negative effect on the growth and development of Forsythia. First, cadmium stress inhibits root growth in forsythia.
The root system is an important organ for plants to absorb water and nutrients, but the toxicity of cadmium will cause the physiological function of root cells to be damaged and root growth to be restricted.
This not only reduces the ability of forsythia to absorb water and nutrients from the soil, but also affects the overall growth and development of the plant.
Second, cadmium stress interferes with the physiology of forsythia leaf. Leaves are the main organs of plants for photosynthesis, but the accumulation of cadmium will destroy the structure and function of chlorophyll and inhibit the progress of photosynthesis.
This leads to a decrease in the photosynthetic efficiency of Forsythia leaves and a decrease in energy synthesis, affecting plant growth and biomass accumulation.
In addition, cadmium stress can also negatively affect the physiological metabolism of forsythia. The accumulation of cadmium interferes with the metabolic pathways of Forsythia, inhibits the synthesis of proteins and nucleic acids, reduces enzyme activity, interferes with the biochemical processes of plants.
This can lead to physiological and metabolic disorders in Forsythia, affecting its ability to resist adversity.
The role of Bacillus subtilis under cadmium stress
Bacillus subtilis is a common probiotic belonging to the Bacillus family. It has many advantages, such as widespread presence in soil, high biomass yield, strong stress tolerance, fast growth rate, etc.
Bacillus subtilis is widely used in agriculture and the environment and is considered a beneficial microbial resource. Due to its excellent characteristics, the application of Bacillus subtilis under cadmium stress has attracted widespread attention.
The researchers found that Bacillus subtilis has the ability to degrade cadmium and can reduce the toxicity of cadmium to plants through mechanisms such as adsorption and detoxification.
In addition, Bacillus subtilis can also enhance the tolerance of plants to cadmium stress by activating the plant's defense system and improving the antioxidant capacity of plants.
The tolerance of Bacillus subtilis to cadmium is an important basis for its function under cadmium stress. Studies have shown that Bacillus subtilis has a high resistance to cadmium.
This is due to the fact that Bacillus subtilis has a variety of adaptation strategies and tolerance mechanisms. First, Bacillus subtilis can reduce the absorption and accumulation of cadmium by accumulating endogenous metal ions such as calcium, zinc, etc.
Secondly, Bacillus subtilis can secrete some special metal-binding proteins to form stable chelated complexes and reduce the toxicity of cadmium to cells.
In addition, Bacillus subtilis can also regulate the permeability and ion transport system of its cell membrane to maintain intracellular and extracellular ion balance and enhance cadmium tolerance.
The promotion effect of Bacillus subtilis on forsythia under cadmium stress is one of the focuses of research. Experiments have shown that Bacillus subtilis can significantly increase the growth and biomass accumulation of Forsythia.
First, Bacillus subtilis increases the plant's ability to absorb water and nutrients from the soil by promoting the development and growth of Forsythia root system.
The root system is the nutrient absorption organ of plants, and Bacillus subtilis can increase the surface area of the root system and the number of root hairs, increase the contact area between the root system and the soil, thereby enhancing the adaptability of forsythia to cadmium stress.
Secondly, Bacillus subtilis enhances plant resistance to cadmium stress by regulating the antioxidant system of Forsythia. Cadmium stress causes forsythia to produce too many reactive oxygen radicals, causing oxidative damage.
Bacillus subtilis can reduce the accumulation of reactive oxygen species and protect cells from oxidative damage by activating the antioxidant enzyme system of plants (such as superoxide dismutase, peroxidase, etc.) and non-enzymatic antioxidant substances (such as glutathione, ascorbic acid, etc.).
In addition, Bacillus subtilis can also enhance the stress tolerance of plants by inducing the expression of forsythia's defense genes.
Studies have found that Bacillus subtilis can promote the expression of a series of anti-stress genes in Forsythia, such as genes encoding antioxidant enzymes, protein synthesis regulators and transcription factors.
The expression of these genes can enhance the tolerance of forsythia and improve its ability to adapt to cadmium stress. In summary, Bacillus subtilis exerted a positive effect on the growth physiology of Forsythia under cadmium stress.
It enhances Forsythia's tolerance to cadmium stress by enhancing the root development of Forsythia, regulating the antioxidant system and inducing defense gene expression.
Mechanism of the influence of Bacillus subtilis on the growth physiology of Forsythia
One of the mechanisms by which Bacillus subtilis positively affects the growth physiology of Forsythia under cadmium stress is through its adsorption and detoxification of cadmium.
Bacillus subtilis has a high adsorption capacity and can reduce its accumulation in soil and plants by adsorbing cadmium.
The polysaccharides, proteins and extracellular polymers on the surface of Bacillus subtilis have a certain affinity, which can combine with cadmium ions to form complexes and reduce the toxicity of cadmium to plants.
In addition, Bacillus subtilis also reduces cadmium toxicity through a detoxification mechanism.
It can secrete a variety of enzymes, such as superoxide dismutase, peroxidase and dehydrogenase, which can degrade and convert cadmium ions and their metabolites, reducing cadmium damage to plant cells.
In addition, Bacillus subtilis can also synthesize and secrete some small molecule compounds, such as glutathione, proline and polyphenols, which have strong reducing and chelating ability, and can form stable complexes with cadmium to reduce the toxicity of cadmium.
The promoting effect of Bacillus subtilis on the growth of Forsythia is closely related to its promoting effect on the root system of Forsythia. Under cadmium stress, Bacillus subtilis is able to increase the growth and development of forsythia root system.
Studies have shown that Bacillus subtilis increases the viability and growth rate of roots by inducing the expression of genes related to root development.
In addition, Bacillus subtilis can increase the number and length of root hairs and improve the ability of roots to absorb water and nutrients in the soil.
Bacillus subtilis establishes a good mutually beneficial symbiotic relationship with the root system of Forsythia through rhizosphere symbiosis. It is able to secrete plant growth hormones such as auxin and gibberellin, promoting the branching and growth of forsythia root system.
At the same time, Bacillus subtilis is able to break down organic matter in the soil and provide the nutrients that plants need. These effects of promoting root development make forsythia root system better adapt to cadmium stress environment and enhance the growth and stress resistance of forsythia.
The promoting effect of Bacillus subtilis on forsythia under cadmium stress also involves its regulation of forsythia antioxidant system.
Cadmium stress causes forsythia to produce large amounts of reactive oxygen radicals, causing oxidative damage. Bacillus subtilis regulates the antioxidant system of Forsythia and enhances the scavenging capacity of plants for reactive oxygen species.
Bacillus subtilis enhances the antioxidant capacity of Forsythia by inducing the activation of the antioxidant enzyme system.
Antioxidant enzymes include superoxide dismutase, peroxidase, and ascorbate peroxidase, which convert reactive oxygen radicals into harmless substances and reduce their damage to cells.
Bacillus subtilis also increases the content of forsythia antioxidants such as glutathione, vitamin C and vitamin E. These antioxidants have powerful free radical scavenging powers and protect cells from oxidative damage.
In summary, the effects of Bacillus subtilis on the growth physiology of Forsythia under cadmium stress are mainly realized through adsorption and detoxification, root promotion effect and antioxidant system regulation.
Together, these mechanisms promote forsythia's tolerance to cadmium stress and improve its growth and ability to adapt to adversity.
In-depth study of the mechanism of action of Bacillus subtilis is helpful to provide new ideas and methods for cadmium pollution control and improvement of plant stress tolerance.
Bibliography:
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[2] CHEN Yuting, SHENG Guangyao, XIE Kangying, et al. Study on cadmium resistance acclimation and cadmium adsorption characteristics of Bacillus subtilis[J].Industrial Water Treatment,2021,41(2):97-102.)